Build-up Model Research Articles

A New Prediction Model of Annular Pressure Buildup for Offshore Wells

Subsea wellheads and Christmas trees are commonly utilized in deepwater oil and gas development. However, the special structure of subsea wellheads makes it difficult to monitor casing–casing annular pressure buildup, which in turn poses a greater risk to the integrity of the wellbore. In order to analyze the effect of changes in the casing-free section and the sealed section on the variation in annulus volume, a new annular pressure buildup model of casing-cement sheath-formation deformation was established and verified according to the elastic deformation theory. Furthermore, the influence of casing deformation on annulus pressure buildup was analyzed. Results indicate that the error of annulus pressure buildup predicted by the multi-string mechanical model proposed in this paper that considers the deformation of the casing sealing section is approximately 13% lower than the one that does not consider this factor. This paper provides guidance for the design of casing strings in deepwater oil and gas wells, ensuring safe production.

Structural build-up model for three-dimensional concrete printing based on kinetics theory

Structural build-up model for three-dimensional concrete printing based on kinetics theory

Prediction of Coaxial Rotor Hub Flow Using Mercury Framework

Rotor hubs are predominantly responsible for the parasitic drag encountered by high-speed rotorcraft. To gain a deeper understanding of the fluid dynamics around rotor hubs, simulations of counter-rotating coaxial rotor-hub flows were conducted, which was subsequently followed by a corroborative experiment at Pennsylvania State University. The simulation process employed a computational fluid dynamics framework termed “Mercury,” which utilizes an unstructured/Cartesian multimesh paradigm. This process incorporated Spalart???Allmaras delayed detached eddy simulation turbulence modelling for an accurate representation of the flow. The investigation into the coaxial hub flow physics was conducted at two different advance ratios: 0.25 and 0.6, constructed by building up the hub components. The interaction between the hub and fairing components led to an increase in the average hub drag and caused unsteady harmonics in the hub and fairing drags. Furthermore, it was noted that different advance ratios affected the drag and wake structures. The complete hub model was then simulated in a water tunnel with an advance ratio of 0.25. Predictions of mean and unsteady drag, as well as mean wake velocity fields, were compared with the experimental results. Overall, the mean wake velocity field from the simulation qualitatively aligned with the experimental results, especially in the near-wake region. Additionally, the buildup model analysis significantly aided in understanding the intricate wake structures surrounding the hub.

Long-term olfactory enrichment promotes non-olfactory cognition, noradrenergic plasticity and remodeling of brain functional connectivity in older mice

Brain functional and structural changes lead to cognitive decline during aging, but a high level of cognitive stimulation during life can improve cognitive performances in the older adults, forming the cognitive reserve. Noradrenaline has been proposed as a molecular link between environmental stimulation and constitution of the cognitive reserve. Taking advantage of the ability of olfactory stimulation to activate noradrenergic neurons of the locus coeruleus, we used repeated olfactory enrichment sessions over the mouse lifespan to enable the cognitive reserve buildup. Mice submitted to olfactory enrichment, whether started in early or late adulthood, displayed improved olfactory discrimination at late ages and interestingly, improved spatial memory and cognitive flexibility. Moreover, olfactory and non-olfactory cognitive performances correlated with increased noradrenergic innervation in the olfactory bulb and dorsal hippocampus. Finally, c-Fos mapping and connectivity analysis revealed task-specific remodeling of functional neural networks in enriched older mice. Long-term olfactory enrichment thus triggers structural noradrenergic plasticity and network remodeling associated with better cognitive aging and thereby forms a promising mouse model of the cognitive reserve buildup.

Противоречия экономики России и механизм их разрешения в условиях импортозависимости

The article examines the modern economic model of Russia and the gaps in the existing import substitution policy. In the course of the work, contradictions of economic institutions were identified, the structural causes of the crisis of the debt build-up model, the question of the introduction of a sovereign development plan was raised, the definition of the plan was given, conditions for sustainable economic growth were described, a model of the economy of innovative development was proposed, taking into account the mistakes of the “debt build-up economy” with the aim of developing Russia as a center of global importance. Based on the analysis, the proposals for the transition to a new economic policy and the use of tools for its implementation on the ba-sis of a system of short- and long-term state planning of socio-economic development are substantiated. A methodology for the formation of a unified strategy for socio-economic development is proposed in order to mitigate emerging strategic risks in the context of external aggression.

Undrained cyclic loading of pyroclastic soils: a new pore water pressure build-up model

Undrained cyclic loading of pyroclastic soils: a new pore water pressure build-up model

Material level analytical model of total ionizing dose induced DC characteristics shift for FDSOI IC design

A charge build-up model implemented in a netlist coupled with L-UTSOI model, which takes into account the deposited dose as an input parameter, is presented for Fully Depleted Silicon On Insulator (FDSOI) transistors. The model is based on the rate equations governing the physical processes of the charge build-up in the oxides. Based on in-house irradiation measurement, our model is calibrated on experimental Id-Vg characteristics in order to find the model parameters and extract the contribution of the oxide and interface trapped charges.

Insight into the role of early C3A hydration in structural build-up of cement paste

This research sheds light on the two origins of C3A hydration in structural build-up of cement paste. The largest critical strain is associated with colloidal interaction, whereas the smallest critical strain originates from the cohesion between calcium sulfoaluminate hydrate (CA$H) particles. Interestingly, we have found that the structural build-up primarily relies on the total colloidal interaction within 2 h of hydration rather than the cohesion between CA$H particles. In C3A-gypsum-CaCO3 pastes, a two-stage structural build-up was observed. The swift progression within the first tens of minutes can be traced back to the augmentation in the number of bonds (solid volume fraction), which then proceeds to the bond strength (colloidal interaction between two flocculated particles). The subsequent slow, linear development is attributed to the strengthening of bonds. As a result of this analysis, a time-dependent model for structural build-up was established. Two rates, namely Acol and ACA$H, were employed to illustrate the impact of the strength and number of bonds. This model is proven to be well-suited for analyzing cement paste within the initial tens of minutes.

Integrated tire wear buildup and rainfall-runoff model to simulate tire wear particles in stormwater

This paper presents an approach to integrate tire wear buildup and rainfall-runoff models to simulate tire wear buildup on road surfaces and its subsequent transport in stormwater runoff events. To do so, a buildup model is presented based on vehicle kilometers traveled, vehicle type, vehicle speed, and road roughness within a watershed. This buildup model was integrated into an EPA SWMM model that simulated the runoff of tire wear particles in twelve watersheds in the San Francisco, CA bay area. Results demonstrate that tire wear particle buildup within the watersheds ranged between 0.4 and 0.51 (kg/km2) per hour. Applied to the SWMM model, total event mean tire wear concentrations ranged between 0.5 and 67 μg/L. These concentrations were linearly correlated to depth-integrated samples collected at the outlet of each of the watersheds (R2 = 0.66). The proposed modeling approach can ultimately be applied to create solutions to an emerging stormwater contaminant.

Predicting stormwater nitrogen loads from a cold-region urban catchment in year 2050 under the impacts of climate change and urban densification

Urban stormwater is a primary source of pollution for receiving water, but there is a shortage of studies on pollutant loads from urban catchments in cold regions. In this study, we coupled a build-up and wash-off model (in Mike Urban) with a climate change model to assess the impacts of climate change and urban densification on stormwater nitrogen loads (TN, TKN, NOx-N, and TAN) in an urban catchment in Canada. We calibrated and validated the Mike Urban model against observed event mean concentrations and nitrogen loads from 2010 to 2016. Results show that the nitrogen loads were mainly governed by rainfall intensity, rainfall duration, and antecedent dry days. Future precipitation data were downscaled using the Global Climate Models (GCMs), and three different Representative Concentration Pathways (RCP 2.5, RCP 4.5, and RCP 8.5) were used. Modeling results show that the TN, TKN, NOx-N, and TAN loads in 2050 will increase by 28.5 - 45.2% from May to September under RCP 2.5 compared to those from 2010 to 2016, by 34.6 - 49.9% under RCP 4.5, and by 39.4 - 53.5% under RCP 8.5. The increase of our projected TN load (from 1.33 to 2.93 kg·N/ha) is similar or slightly higher than the limited studies in other urban catchments. This study provides a reference for predicting stormwater nitrogen loads in urban catchments in cold regions.

Deep-Learning Model for Buildup of Ionization Defects in Bipolar Junction Transistors

Deep-Learning Model for Buildup of Ionization Defects in Bipolar Junction Transistors

A coupling prediction model of annular pressure build-up for deepwater oil and gas wells during transient-state testing

To accurately predict annular pressure build-up of deepwater high pressure-high temperature oil and gas wells during the transient-state testing, a coupling prediction model of trapped & untrapped annular pressure build-up is proposed. For the short-term process of gas well transient testing, a wellbore transient heat transfer model has been established. Then the improved coupling model of trapped & untrapped annular pressure build-up is established, which is not only novelly considering fluid thermodynamic properties (isobaric expansion coefficient and isothermal compression coefficient) under high pressure-high temperature conditions and annulus fluid mass changes of untrapped annulus, but also considering annulus volume changes. For precise coupling calculating the annular pressure build-up, the annulus is divided into infinitesimal grid cells along well depth. The impact of different considering factors, testing times, testing production rates, formation permeability and cement sheath sealing positions on the annular pressure build-up in the model is investigated. The results show that conventional models (high pressure-high temperature properties and mass changes of the fluid are not considered) will greatly overestimate the annular pressure build-up; as the testing time increases, the impact of untrapped annulus fluid mass changes on the annular pressure build-up will gradually take the dominant role; reasonably optimizing the setting of untrapped annulus open hole section in high permeability formations and increasing the distance between cement sheath and the upper casing shoe can effectively relieve the increasing annular pressure build-up. These findings can achieve accurate prediction of trapped and untrapped annular pressure build-up, and play an important role in guaranteeing the wellbore integrity and safety of deepwater oil and gas wells during transient-state testing.

Optimizing first flush diverter for urban stormwater pollution load reduction by most efficiently utilizing first flush phenomena

In order to find the optimal design of first flush diverter, this study shifts the focus of first flush research from the existence of first flush phenomenon to utilization effect of the phenomenon. The proposed method consists of four parts: (1) key design parameters, which describing key structure of first flush diverter rather than first flush phenomenon; (2) continuous simulation, which replicating the uncertainty by using the full scope of runoff events that might occur over the years analyzed; (3) design optimization, through an overlapped contour graph of key design parameters and key performance indicators that are relevant to but different from conventional indicators describing first flush phenomena; (4) event frequency spectra, which presenting the diverter's behavior at daily temporal resolution. As an illustration, the proposed method was used to determine design parameters of first flush diverters for roof runoff pollution control in the northeast of Shanghai. The results show that annual runoff pollution reduction ratio (PLR) was insensitive to buildup model. This greatly reduced the difficulty of buildup modeling. The contour graph was useful in finding the optimal design, i.e., the optimal combination of design parameters that could meet PLR design goal with most concentrated first flush on average (quantified by MFF). For instances, the diverter could achieve PLR = 40% with MFF >1.95, and PLR = 70% with MFF = 1.7 at most. Pollutant load frequency spectra were generated for the first time. They showed that a better design reduced pollutant load more stably while diverting less volume of first flush within almost each runoff day.

The build-up approach. Could it be an alternative to the CAPM?

Background: The paper contains the economic background for implementing the build-up approach as an alternative method to the Capital Assets Pricing Model (CAPM).
 Research purpose: This study aims to consider company-specific risk premium that makes cost estimation unique, subjective, and different within the economic factors that may be considered and used for entity cost of equity estimation, valuation, or other economic metrics.
 Methods: The author analyzes the most recent literature on companies’ cost of equity and estimating specific risk premiums. Each component of the cost of capital in the build-up approach was analyzed and interpreted. The petroleum industry was analyzed between 2011 and 2021. The Mercer model for specific risk was used.
 Conclusions: The build-up approach seems the best choice to calculate equity costs in a turbulent economic environment. However, due to its mathematical structure, it could be criticized for the huge subjectivity in the assessment risk premium rate. The key to using this method is to make it less subjective. This paper suggests an approach that minimizes the subjectivity in the build-up model. So far, there is no comprehensive analysis of the Polish market that has been prepared from the perspective of the petroleum industry’s specific risk premium. This research creates possibilities for further comprehensive analysis related to models to calculate company risk premiums and the factors that affect them.

Soil Dynamic Constitutive Considering Post-Liquefaction Deformation and Reversible Pore-Water Pressure

In the seismic response analysis of liquefiable sites, the existing soil dynamic constitutive model is challenging to simulate saturated sand’s post-liquefaction deformation, and the current pore-water pressure buildup model cannot reflect the decrease in the actual pore-water pressure under unloading stress. We aim at these problems to propose a feasible and straightforward time-domain post-liquefaction deformation constitutive model through experimental analysis and theoretical research, consisting of reversible pore-water pressure. According to the dynamic triaxial test data, the regularities of large deformation stress and strain behavior of the saturated sand after liquefaction are obtained, and the corresponding loading and unloading criteria are summarized. Combined with the effective stress constitutive model proposed by the author, a soil dynamic constitutive that can describe saturated sand’s post-liquefaction deformation path is obtained. According to the test results, the model can simulate the deformation of saturated sand during the whole liquefaction process. The self-developed program Soilresp1D realized the dynamic response analysis of the liquefiable site, and the results were compared with the experimental results. It shows that the model based on the effective stress-modified logarithmic dynamic skeleton and post-liquefaction deformation constitutive can be directly applied to the dynamic response analysis of the liquefiable site.

STITCH: A Subgrid-scale Model for Energy Buildup in the Solar Corona

The solar corona routinely exhibits explosive activity, in particular coronal mass ejections and their accompanying eruptive flares, which have global-scale consequences. These events and their smaller counterparts, coronal jets, originate in narrow, sinuous filament channels. The key processes that form and evolve the channels operate on still smaller spatial scales and much longer timescales, culminating in a vast separation of characteristic lengths and times that govern these explosive phenomena. In this article, we describe implementation and tests of an efficient subgrid-scale model for generating eruptive structures in magnetohydrodynamics (MHD) coronal simulations. STITCH—STatistical InjecTion of Condensed Helicity—is a physics-based, reduced representation of helicity condensation: a process wherein small-scale vortical surface convection forms ubiquitous current sheets and pervasive reconnection across the sheets mediates an inverse cascade of magnetic helicity and free energy, thereby forming the filament channels. We have developed a formalism, STITCH, that abstracts these complex processes into a single term in Ohm’s law and the induction equation that directly injects tangential magnetic flux into the low corona. We show that our approach is in very good agreement with a full helicity condensation calculation that treats all of the dynamics explicitly, while enabling substantial reductions in temporal duration and spatial resolution. In addition, we illustrate the flexibility of STITCH at forming localized filament channels and at energizing complex surface flux distributions that have sinuous boundaries. STITCH is simple to implement and computationally efficient, making it a powerful technique for physics-based modeling of solar eruptive events.

Modeling the Impact of the Viscoelastic Layer Thickness and the Frictional Strength to the Lithosphere Deformation in a Strike-Slip Fault: Insight to the Seismicity Pattern along the Great Sumatran Fault

As an earthquake is capable of causing significant losses, a strain buildup and release model following an earthquake is of importance for mitigation purposes. In this study, we aim to model strain buildup and release on a strike-slip fault which consists of elastic–brittle (upper crust) and elastic–viscous (lower crust and upper mantle) layers using a finite element model. The fault strength during strain buildup is controlled by the friction coefficient and cohesion, in addition to the viscoelastic parameter, as shown in the deformation model using Maxwell’s material. In the strain buildup model, we found that the differential stress on the elastic layer is larger than that on the viscoelastic layer and that the differential stress increases with the thickness of the elastic layer. When the viscoelastic layer is thinner, the deformation observed on the surface is larger. However, the differential of stress in the strain release model on the elastic layer is smaller than that on the viscoelastic layer, which shows the transfer stress from the lower crust and upper mantle to the upper crust. Using the knowledge gained by varying the thickness and frictional strength of the lithosphere, we discuss the seismicity pattern observed along the Great Sumatran Fault.

A novel approach for measuring particle settling and settled bed build-up velocities in concentrated slurries using electrical resistance tomography

Electrical Resistance Tomography (ERT) has been used to detect different phases based on differences in conductivities in multiphase systems. For the first time, ERT is used in this work to study solids settling and settled bed build-up velocities in a slurry of glass particles and glycerol solution. It measures the particles' position via mixture conductivities, which determine solids concentration at different heights. Development of the solids settling velocity model relies on the movement of particles instead of tracking the solid-liquid interface. Experimental solids settling velocity value decreases with increasing solids concentration and liquid viscosity, agreeing with estimations from Richardson and Zaki's model. The settled bed build-up model uses mass balance and ERT data to predict build-up velocity, which increases with increasing solids concentration and decreasing liquid viscosity. Results demonstrate that, as a direct and non-invasive method, ERT could simultaneously measure the solids settling and settled bed build-up velocities in slurries. • Electrical Resistance Tomography is used to measure solids settling velocity. • Settling velocity decreases as solid concentration and liquid viscosity increase. • Settled bed buildup velocity model developed using tomography data. • Βuildup velocity is higher at higher solids concentration and lower viscosity. • A relationship between solids settling and buildup velocities is established.

Boil-off gas emission from the fuel tank of a LNG powered truck

LNG fueled vehicles are growing in many countries as a convenient solution for heavy duty and collective passenger transport due to the development of a capillary refueling infrastructure. Due to the known pressure build-up phenomenon, long duration parking of vehicles could cause flammable gas emission and potential explosive atmospheres in closed environments like repair workshops. In this paper, a model of pressure build-up and discharge is applied to small LNG tanks to evaluate the consistency of the phenomenon when pure methane is taken as reference for the calculation rather than the natural gas mixture. Moreover, it is compared with flow and pressure measurements performed for the first time, through a specifically developed suitable test facility. The scope of this study is to improve the awareness about the flammable gas emission from LNG fueled trucks in the safety framework. The expected results can be used to design ventilation systems to lower the flammable gas concentration and mitigate the explosion risk in closed environments.

Improved buildup model for radiation-induced, defects in MOSFET isolation oxides

Ionizing radiation induces defects in STI oxides in current MOSFETs. These defects may degrade the performance of the MOS circuit. Analytical models for the buildup of these defects during the radiation exposure are available in literature. In this paper, we introduce an improved model to estimate the buildup of defects that is valid for both low and high radiation doses. Our improved model is compared to published data showing its validity.